METHODS: The recombinant Mhp170 (rMhp170), Mhp274 (rMhp274), and Mhp336 (rMhp336) proteins were purified from recombinant bacteria. Fifty-two six-week-old SPF female BALB/c mice were divided into five groups: a commercial inactivated vaccine-immunized group, three recombinant protein-inoculated groups, and a PBS-treated group. The physical parameters and body weights of the mice were observed during the experiment. The lung/body coefficient and macroscopic and microscopic lung lesions were evaluated. IgG and its isotypes IgG1 and IgG2a in serum and BALF and sIgA in BALF were assessed. The levels of IFN-γ, IL-4, and IL-17, in the supernatants of splenocytes and in serum were measured, and the mRNA levels of three cytokines in splenocytes were analyzed. Finally, lymphocyte proliferation after stimulation with corresponding proteins or crude extract of RESULTS: We successfully constructed recombinant bacteria expressing rMhp170, rMhp274, and rMhp336. None of the mice from all groups presented adverse reactions and macroscopic and microscopic lung lesions. rMhp170 and rMhp274 were capable of inducing the production of IgG, IgG1 and IgG2 in serum and BALF, the secretion of IFN-γ, IL-4 and IL-17 in serum, the expression of IFN-γ, IL-4 and IL-17 mRNAs in splenocytes, and high levels of lymphocyte proliferation. Moreover, rMhp274 significantly increased sIgA in BALF. Nevertheless, rMhp336 induced only IgG, IgG1 and IgG2 production in sera
the secretion of IFN-γ and IL-4 in sera and BALF
the expression of IFN-γ and IL-4 mRNAs in the splenocyte population
and lymphocyte proliferation. CONCLUSION: Mhp170 and Mhp274 induced Th1/Th2/Th17 immune responses, and Mhp336 stimulated mixed Th1/Th2-type immune responses, in mice. Our data suggest that Mhp274 is a potential viable candidate for the development of a subunit vaccine for MPS.